Cyanide gold extraction is an economical and simple method for extracting gold from ore, concentrate or tailings, It has a series of advantages such as high recovery rate and strong ore adaptability. Since it was put forward at the end of the 19th century, this method has been widely used in the world gold production and has become the main method of modern gold mine smelting. At present, 90% of the gold mines in the world use cyanide gold extraction, and more than 80% of the gold dressing plants in China use cyanide gold extraction. But its disadvantage is also obvious, the production process produced a large amount of cyanide tailings. Cyanide tailings are initially treated as waste and are traditionally disposed of either by stockpiling or landfill. This not only wastes a lot of land resources, but also exposes the sulfur and heavy metals in the cyanide tailings, such as gold, silver, copper, lead and zinc, as well as cyanide residues in the flotation process, to the air. When exposed to sunlight, rainwater can produce harmful gases and liquids, which can seep into the ground and cause serious pollution to water bodies and soil. In addition, cyanide tailings, which have been processed for many times, have fine particles, which are easy to cause dust in dry or windy weather, affect air quality, pollute atmospheric environment, and do great harm to the environment. It is estimated that the annual economic loss caused by cyanide residue waste pollution can reach hundreds of millions of yuan. The new national hazardous waste list, jointly issued by the ministry of environmental protection and the national development and reform commission and the ministry of public security, came into force on Aug. 1, 2016. The cyanide tailings produced in the process of gold dressing with cyanide are classified as hazardous waste, an environmental protection tax of 1,000 yuan/ton will be levied on hazardous waste, so the gold industry will suffer a devastating blow. Therefore, the recycling of cyanide tailings is not only necessary for the rational development of resources and environmental protection, but also for the improvement of economic benefits and self-development of the gold industry.
The reuse of tailings includes two aspects: First, recovery from the tailings extract useful components, that is, the reselection of tailings; second, use tailings as the basic raw materials to develop new products. At present, most studies on cyanide tailings have focused on how to further extract Au, Ag, Fe, S and other valuable elements in tailings more efficiently, but there is a lack of research on the disposal method of residual waste residue after treatment. The residual residue is also a very important secondary mineral resource and contains a large amount of non-metallic mineral materials, quartz, feldspar, pyroxene, garnet, amphibole and altered clay, mica and other aluminosilicate minerals and calcite, dolomite and calcium magnesium carbonate minerals which can be widely used in building materials, light industry, inorganic chemical industry and other fields.
In conclusion, it will become an important direction of development to prepare high-performance building materials with cyanide tailings as the main raw material. The non-metallic mineral composition in the cyanide tailings is the same as that required for the raw material of ceramsite and can be used as the main raw material for the production of ceramsite. Generally, high temperature sintering is adopted in the preparation of ceramsite. High temperature sintering combined with the method of chlorination roasting, the heavy metals are volatilized in the form of chloride and the ceramsite is fired simultaneously, the whole process is controlled in the same calcination equipment which reduce the process steps, energy consumption and pollution. The method of recovering valuable metals by roasting cyanide tailings to produce ceramsite can not only solve the environmental problems caused by waste residues, but also realize harmless value-added utilization of waste residues and create huge economic benefits. Therefore, the invention relates to a method for recovering valuable metals by roasting cyanide tailings and simultaneously preparing ceramsite has great significance and value.